Zangzang Bao

The original is descended from the Japanese chocolate-cornet and croissant idea, recast as a cocoa-buried chocolate bun. In China it was popularised by the Beijing shop Bad Farmers and Our Bakery, which entered the Sanlitun district in May 2017 selling it in limited runs; the early push fell flat until, in December 2017, a wave of celebrities posted themselves eating it on Weibo and it shot onto the trending lists as one of that year's viral foods. Through early 2018 it went fully commercial, with industrial bakeries and chain shops rolling out their own versions, and it became the defining over-the-top viral bake of the era — before the hype, as such hype does, cooled.

It looks deliberately filthy: a dark, cocoa-caked lump that powders your fingers before you have even bitten in. The first bite shatters — flaky, buttery laminated layers, crisp at the edges — and then gives way to a soft, warm, bittersweet chocolate core that smears across your lips. The cocoa dusting is dry and faintly bitter against the sweet ganache. It is best warm, when the centre is loose and molten; cold, the chocolate stiffens and the layers lose their snap.

The flaky shell is lamination. Butter is folded into the dough again and again to build dozens of alternating layers of dough and fat; in the oven the water in the butter flashes to steam and pushes the dough layers apart, and the heat sets them into crisp leaves — the same physics as a croissant. The filling is ganache, chocolate emulsified into warm cream, which stays soft and turns molten when the bun is warmed. The cocoa coat is pure powder, with none of cocoa butter's melt, so it reads dry and bitter — a deliberate counterweight to the sweet, fatty interior, and the source of the mess.